Reverse operation safety circuit

ABSTRACT

A control circuit for a lawn tractor having an engine and a power take off driven implement. The control circuit includes an inhibit circuit component for preventing operation of a power take off driven implement with the tractor in reverse. Two versions of the inhibit circuit are disclosed, one grounds an engine magneto and a second disables an electric clutch for coupling the power take off to the driven element. The circuit includes first and second override switches and an override circuit component that allows operation of a power take off driven implement while the lawn tractor is in reverse after the first and second override switches are activated in a proper order by a tractor operator.

FIELD OF THE INVENTION

The present invention relates generally lawn and garden tractors andsimilar vehicles. In particular, the present invention relates to areverse operation safety circuit for such a vehicle.

BACKGROUND OF THE INVENTION

Vehicles such as some lawn and garden tractors have power take offs(PTOs) that are used to drive implements such as mower blades. Priorlawn and garden tractors with PTOs have included interlock circuits thatprevent engagement of the PTO driven implement when the vehicle is inreverse. Under certain conditions, operation of a PTO driven implementwhile the vehicle is in reverse is desirable. Various override systemshave been proposed that allow operation of a PTO driven implement inreverse.

Override systems have been developed that use a momentary over-rideswitch that latches an over-ride relay. The over-ride relay is unlatchedwhen certain other conditions are met, like shifting out of reverse. Oneproblem with override systems that rely on relays is that relays canstick in a closed state or the relay may not may not connect whenenergized. Use of multiple relays and implementing time delays canresult in complex, expensive and difficult to service override systems.

One proposed system uses a four-position ignition switch (Off, Run withover-ride on, Run with over-ride off, and Start). In that system theuser must turn the key to the start position to start the engine, thusresetting the over-ride on engine restart. The ignition switch springreturns the key from the Start position to the Run with over-ride offposition, requiring an additional intentional movement of the key by theuser to select Run with over-ride on option.

U.S. published application 2004-0201286 to Harvey et al. entitled“Reverse Operation Safety Circuit” concerns a safety system for a ridinglawn mower that prevents powered operation of a PTO driven implementwhile the tractor is in reverse unless an override switch is “ON”. Theoverride switch may be a sustained action two position switch and thePTO driven implement may be a lawn mower blade. In one embodiment, theoverride switch does not allow the engine to start if the overrideswitch is on. In one embodiment, the override switch cooperates with anoperator presence switch to prevent operation of the PTO drivenimplement when the override switch is on and the operator is notpresent. The disclosure of this published application to Harvey et al.is incorporated herein by reference.

SUMMARY

The present invention concerns a safety system for a riding lawn mowerthat prevents powered operation of a PTO driven implement if the tractoris shifted to reverse unless an over-ride condition has beenestablished.

An exemplary control circuit for a lawn tractor includes an inhibitcircuit component for preventing operation of a power take off drivenimplement with the tractor in reverse and first and second overrideswitches. An override circuit component allows operation of a power takeoff driven implement while the lawn tractor is in reverse after thefirst and second override switches are activated by a tractor operator.

In a preferred exemplary embodiment, the control circuit, an overrideswitch and an indicator are all mounted on a single circuit board. Inaccordance with another aspect of the preferred exemplary embodiment,this circuit board is part of an ignition module that mounts to a ridinglawnmower dash board and which includes a second of the two overrideswitch contacts.

Additional features of the invention will become apparent and a fullerunderstanding will be obtained by reading the following detaileddescription in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a lawn and garden tractor equipped with areverse operation override switch and additional safety switches;

FIG. 2 is a perspective view of an ignition switch module or housingthat supports a multi-position ignition switch and reverse operationsafety circuit;

FIG. 3 is a front plan view of the ignition switch module of FIG. 2;

FIG. 4 is a rear plan view of the ignition switch module of FIG. 2;

FIG. 5 is an exploded perspective assembly view of the ignition switchmodule of FIG. 2;

FIG. 5A is an enlarged plan view of a portion of a gasket for use withthe exemplary embodiment of the invention;

FIG. 5B is an enlarged view of a portion of the conductive trace on acircuit board used with an exemplary embodiment of the invention; and

FIGS. 6A-6C are circuit schematics of an override circuit for use withthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a lawn and garden tractor 12 that allows operation ofa PTO driven implement 16 when the tractor is in reverse. In theillustrated embodiment, the PTO driven implement 16 is a mower blade. Itshould be readily apparent that the circuit 100 (FIGS. 6A-6C) discussedbelow could be applied to other PTO driven implements. For example, thePTO driven implement could be a snow thrower. In the exemplaryembodiment, the tractor 12 implements a mow in reverse capability usinga plurality of switches. The system illustrated by FIG. 1 includes anoperator presence switch 24, a reverse switch 26, a multi-positionignition switch 28, a PTO switch 30, and an engagement switch 32.

The illustrated operator presence switch 24 is positioned below a seat34 to sense the presence of an operator on the seat. In the illustratedembodiment, a lever 27 controls whether the lawn and garden tractor isin “Forward” or “Reverse.” An actuator 29 of the illustrated reversesensing switch 26 is in communication with the lever, such that theposition of the actuator 29 indicates whether the lawn and gardentractor is in “Forward” or “Reverse.” Referring to FIG. 2, theillustrated ignition switch 28 is a multi-contact key switch supportedby a module 50 that mounts to a tractor dashboard 31. When the ignitionkey is moved to a start position a set of ignition switch contacts closeto selectively energize a starter motor with voltage from a battery 38(FIG. 6C) to start the engine 41. In the exemplary embodiment, theignition switch 28 closes a path between the battery 38 and a startersolenoid to energize the starter motor with the battery 38.

On some lawn and garden tractors, movement of an actuator 42 of the PTOswitch 30 between an “ON” position and an “OFF” position causesengagement and disengagement of the PTO driven implement respectively.On these tractors, a PTO switch 30 is coupled to a powered actuator orclutch that engages and disengages the PTO driven implement based on theposition of the PTO switch actuator. On other lawn and garden tractors,the PTO driven implement 16 is engaged and disengaged by a manualmovement of a mechanical PTO engagement linkage. On these tractors, thePTO switch actuator is moved by movement of the PTO engagement linkageand thereby senses engagement and disengagement of the PTO drivenimplement. An engagement switch 32 senses engagement of a brake 44and/or engagement of a drive transmission 46. In the illustratedembodiment, a single switch senses the position of a pedal 47 thatengages the brake and disengages the transmission 46 when depressed. Inanother embodiment, separate switches sense engagement of the brake andthe transmission.

FIGS. 2-5 illustrate details of the ignition switch module 50. Themodule includes a dashboard engaging lip 52 that extendscircumferentially around an outer perimeter of the module. A modulehousing defines a cavity bounded by a rectangular top surface 54, acurved bottom surface 56, and two side surfaces 58, 60. Flexible fingers62 on the sides have latches 64 at their ends for securing the module tothe dashboard.

An assembly view of the switch module 50 is illustrated in FIG. 5. Asseen in that figure, the module 50 has a front or outwardly facingsurface 66 that defines a cutout 68. During assembly of the module 50the ignition switch 28 is pushed through the cutout 68 so that latches70 of a switch housing 28a seat within corresponding notches 72 definedby the cutout 68. A faceplate 74 bounds portion of the cutout 68 and isapplied to the front surface 66 of the module. This faceplate includesindicia that conveys information to an operator regarding operation ofthe ignition switch 28.

The exemplary ignition switch 28 is a four position switch having a keyslot 76 for insertion of a key for turning on the tractor. Asillustrated in FIG. 3, the key slot is oriented in a stop position 78.Three other positions or key orientations are start 79, run 80, and arun with reverse override 81. The switch includes a plurality of switchcontacts 82 on a back side of the switch 28 that are exposed forcoupling to circuitry when the module 50 is mounted to the lawn mowerdash board 31. In the start position of the ignition switch, thesecontacts complete a circuit that energizes a starter motor by applying abattery voltage to the tractor's starter solenoid.

The module 50 supports a printed circuit board 83 that is supportedwithin a module interior by a molded plastic carrier 84. Overlying thecircuit board 83 is a flexible rectangular gasket or membrane 86 havinga front surface 88 that is positioned between an inner surface of themodule's interior and a forward facing surface of the printed circuitboard 83. The gasket has a lip 90 that overlies a corresponding outerborder of the carrier 84. When pushed into the module, the outer borderof the gasket is compressed against the circuit board and impedes waterin the region of the module from leaking into contact with the printedcircuit board.

The gasket has two raised portions 92, 93 that are visible throughcutouts in the module 50. A first raised portion covers a light emittingdiode that is activated when the tractor is in an override condition. Asecond raised portion includes a warning indicia and overlies apushbutton override switch 130 that forms part of the circuit 100depicted in FIGS. 6A-6C. During assembly of the module 50 a number ofcircuit contacts 94 that extend rearwardly from the printed circuitboard 83 are pushed through openings of a male connector 95 formedintegrally with the carrier 84. A female connector engages thisconnector 95 to couple the circuit 100 to other circuit components ofthe tractor. A tab 96 integral with the carrier 84 extends downward andincludes an opening through which a connector 97 extends. The exemplaryconnector 97 is a screw that threads into a boss (not shown) in themodule housing. The gasket, printed circuit board, and carrier all fitwithin a cavity defined by a generally horizontal ledge 98 in the modulehousing that extends across the width of that housing.

The disclosed circuit 100 implements a dual motion override. Batterypower is applied to the circuit 100 when the ignition is switched ormoved from the stop position 78. Use of the driven implement 16 whilemoving in reverse requires moving the ignition switch to the overrideposition 81 and then activating a push button switch 130 before shiftingto reverse. If this dual motion process is not performed, putting thetractor into reverse with the engine running will deactivate the powertake off implement 16. In a tractor having a manual clutch, theexemplary circuit shorts the engine magneto and in a so-called electricclutch configuration, the circuit 100 energizes a relay to disengage theelectric clutch while allowing the engine to run. The term “mow inreverse” is used herein to describe this override condition because inthe exemplary embodiment the driven element 16 is a riding tractor mowerblade.

FIGS. 6A, 6B, and 6C disclose an override safety circuit 100 havingthree inputs 102, 104, 106 whose state is dictated by the status ofthree tractor switches. A first input 102 is coupled to the reverseswitch 26. When the user moves the lever 27 to a reverse position, theinput 102 is grounded. Grounding the input 102 turns on a transistor Q1,which in turn pulls a collector output 110 of the transistor high. In anon-override situation, this high output from the transistor Q1 will becoupled through a diode 112 (FIG. 5B) to a gate input 114 of a triac116, which turns the triac on. When the circuit 100 is used with amanual pto clutch, the triac 116 is coupled through a PTO clutch switch117 to an engine magneto 118. A clutch engagement lever controls theopen or closed state of this switch When the clutch is manually engagedto actuate the mowing blades, the switch 117 is closed. If the reverseswitch is closed, the triac 116 conducts and pulls the magneto to groundthereby shutting off the engine and disabling mowing in reverse. Asdescribed below, this shorting of the magneto to ground can beoverridden, however, by proper actuation of two override switches.

Directly beneath the triac 116 for use with the manual clutch version ofthe circuit 100 is an electric clutch disable portion of the circuit.This circuit deactivates the electric clutch by activating a relay. Thehigh signal at the collector output 110 turns on a transistor Q9,pulling one side of the relay coil 119 to ground to disengage theelectric clutch.

The circuit 100 includes two flip-flop circuits 120, 122 (FIG. 6A),which are conditioned in response to various tracator switch inputs. Theright most flip-flop 120 has a clock input coupled to a push buttonswitch 130. When the push button switch is closed, a clock input to theright most flip-flop 120 goes high transmitting the input at pin D1 ofthat flip-flop 120 to the Q1 output. When a high output is clockedthrough the flip-flop 120, (to the Q1 output) a transistor 132 (FIG. 6B)is turned on causing a light-emitting diode 134 to conduct and alsopulling low a junction 136 to a low state. This junction 136 is alsocoupled to the collector output 110 from the transistor Q1 coupled tothe reverse input 102 from the transmission switch. Dropping of thevoltage at the junction 136 inhibits activation of the triac 116 (manualclutch) in response to closure of the reverse transmission switchthereby allowing continued operation with the clutch engaged. Similarlya low voltage at the junction 136 also prevents energization of therelay coil 119 for disengaging the electric clutch coil in tractorshaving electronic clutches. It is therefore seen that depending on thestate of the input D1 to the flip-flop 120, when the push button switch130 is activated, the mow in reverse override is implemented. If theproper sequence of conditions occur the override state is achievedregardless of whether the pto is engaged and the pto can be engagedwhile moving the tractor in reverse so long as the override switches arefirst activated in order before the tractor is shifted to reverse

Upon power up of the circuit, a power on reset (high signal) is coupledto both flip-flops 120, 122. This is achieved by a turn on of atransistor Q8 thereby assuring that the output from the Q1 output of theflip-flop 120 is initially low and thereby assuring the override featurehas not been set. Turning to the other flip-flop 122, the D2 input tothis flip-flop 122 is coupled to a voltage source (derived from tractorbattery at inputs 140, 142, FIG. 6C). Receipt of a low to hightransition signal at a clock input 150 transmits a high output at the Q2output of the flip-flop 122.

When the ignition switch 28 is turned to the override position 81, theinput 104 goes low turning off a normally on transistor Q3. When thetransistor Q3 is conducting, a connection 152 coupled to the D1 of theflip flop 120 is held low. When the transistor Q3 turns off alow-to-high transition occurs at the clock input 150 to the flip flop122 and the Q2 output from this flip flop goes high. This causes the D1input to the second flip-flop to be pulled high. Subsequent closure ofthe pushbutton switch 130 will clock a high output to the flip flipoutput Q1 to activate the override state to allow mowing in reverse forexample.

The override state can be reset or turned off in three ways. One is bygetting off the seat (electronic clutch, or activating the brake formanual clutch) causing the input 106 to go low. In the electric clutchversion, the seat switch causes the input 106 to go low and the manualclutch version the brake causes the input 106 to go low. These twoexamples of control of the state of the input 106 are illustrative, andother signal conditioning mechanisms are certainly possible to controlthis state. Since in the manual clutch version, getting off the seatdoes not reset the override, a separate circuit (not shown) disables theengine should the users leave the seat. After an appropriate time delayimplemented by a one-half second delay circuit 160, a reset input (high)is coupled to both flip-flops. The delay is dictated by a charge time ofa capacitor C5 through a conducting transistor Q5.

A second reset occurs if the ignition switch is turned to off therebydeactivating the circuit so that upon the next activation of thecircuit, the power up reset transistor Q8 again resets both flip-flops.The third mechanism for resetting is to switch the ignition switch fromthe mow in reverse position to the run position or normal mowingposition. This causes the transistor Q3 coupled to the override input104 to turn on pulling a base input to the transistor Q7 low to turn thetransistor Q7 on and thereby couple a high pulse to the reset input toboth flip-flops 120, 122. To again put the tractor in reverse overriderequires switching to the run with override position 81 of the ignitionswitch as well as activation of the push button switch 130.

Note, an input 168 from seat switch input 106 is coupled to electricclutch deactivation portion of circuit to automatically disengage theelectric clutch when the operator gets off the seat. The input 168 goeshigh when the seat switch grounds the input 106 and this high signalturns on the transistor Q9 discussed above.

For the manual clutch systems, the override is reset when the parkingbrake is set, not when the operator leaves the seat. Other circuitry,not shown, kills the engine when the operator leaves the seat with theblades on. One side effect is that the triac 116 kills the engine if theparking brake is set with the blades on as indicated by the closed ptoswitch 117. In systems wishing to allow continued blade operation withthe brake on, an additional bypass input 170 is grounded for the manualclutch version of the circuit 100. Grounding this input 170 prevents theparking brake switch from killing the engine when the blades are on.When the input 168 goes high the grounded bypass input 170 prevents thissignal from turning on the triac 114. The input 170 is left floating onelectric clutch units. This allowed a single circuit design to work withelectric and manual clutch units.

Table 1 is a truth table for operating states of the circuit 100 for theelectric clutch version. In this table the acronym MIRO stands for mowin reverse override. TABLE 1 for circuit functionality Push- Outputs Keyswitch SEAT REVERSE button (MAGNETO position Switch Switch Switch andRELAY) Pos 2 (from Occupied Reverse Unpressed Low Outputs Pos 3) (Low)Pos 2 (from Occupied Reverse Unpressed Enables MIRO, thus Pos 3) toPressed mowing in reverse allowed Pos 2 (from Occupied Forward UnpressedMowing allowed; Pos 3) (Low) MIRO is not enabled Pos 2 (from OccupiedForward Unpressed Enables MIRO, thus Pos 3) to Pressed mowing in reverseallowed Pos 2 (from Empty Reverse Unpressed Low Outputs Pos 3) (Low) Pos2 (from Empty Reverse Unpressed Low Outputs Pos 3) to Pressed Pos 2(from Empty Forward Unpressed Low Outputs Pos 3) (Low) Pos 2 (from EmptyForward Unpressed Low Outputs Pos 3) to Pressed Position 1, OccupiedReverse Unpressed Low Outputs 3, or 4 (Low) Position 1, Occupied ReverseUnpressed Low Outputs 3, or 4 to Pressed Position 1, Occupied ForwardUnpressed Mowing allowed; 3, or 4 (Low) cannot enable MIRO Position 1,Occupied Forward Unpressed Mowing allowed; 3, or 4 to Pressed cannotenable MIRO Position 1, Empty Reverse Unpressed Low Outputs 3, or 4(Low) Position 1, Empty Reverse Unpressed Low Outputs 3, or 4 to PressedPosition 1, Empty Forward Unpressed Low Outputs 3, or 4 (Low) Position1, Empty Forward Unpressed Low Outputs 3, or 4 to Pressed

The gasket or membrane 86 which overlies the printed circuit board is anelastomer material, most preferably a liquid silicone gasket materialthat is molded. Other rubber materials are also suitable for use in themembrane The gasket prevents water seepage into the region of thecircuit board. On its inner layer (facing the printed circuit board) thegasket 86 supports a electrically conductive round carbon pill . Thecarbon pill is added to the mold with the liquid silicone as the gasketis formed and upon cooling of the elastomer the carbon pill adheres tothe elastomer material to form an actuator region 200. When the userpresses against the region of the gasket 93 through the cutout in themodule 50 this carbon actuator region 200 bridges conductive traces 202,204 that terminate in a pattern 206 on the printed circuit board toclose the switch 130. In the illustrated embodiment the portion of themembrane 86 overlying the actuation region is orange and the portion ofthe membrane overlying the LED 134 is translucent.

Although the present invention has been described with a degree ofparticularity, it is the intent that the invention include allmodifications and alterations falling within the spirit or scope of theappended claims.

1. A control circuit for a lawn tractor having an engine and a powertake off driven implement; said control circuit comprising: an inhibitcircuit component for preventing operation of a power take off drivenimplement with the tractor in reverse; first and second overrideswitches; and an override circuit component that allows operation of apower take off driven implement while the lawn tractor is in reverseafter the first and second override switches are activated by a tractoroperator.
 2. The control circuit of claim 1 wherein the inhibit circuitcomponent prevents operation of the power take off by shutting down theengine.
 3. The control circuit of claim 1 wherein the override circuitallows operation of the power take off driven implement if the first andsecond override switches are activated in a correct order.
 4. Thecontrol circuit of claim 1 wherein the inhibit circuit has a reverseengagement switch input which changes state when the tractor is shiftedinto reverse to prevent operation of the power take off drivencomponent.
 5. The control circuit of claim 1 wherein the first overrideswitch is coupled to a multi-position ignition switch.
 6. The controlcircuit of claim 5 wherein the second override switch comprises agenerally planar layer of conductive material affixed to a flexiblemembrane that bridges conductive traces on a printed circuit board. 7.The control circuit of claim 1 wherein a low resistance path to groundis created by the inhibit circuit unless the first and second overrideswitches are activated before the tractor is shifted into reverse. 8.The control circuit of claim 1 additionally comprising an operatorpresence switch that senses an operator, the operator presence switchresetting the override circuit to prevent mowing in reverse.
 9. Thecontrol circuit of claim 1 additionally comprising a brake engagementswitch that senses engagement of a brake, the engagement switchresetting the override circuit to prevent mowing in reverse.
 10. Thecontrol circuit of claim 1 wherein the engine is a magneto operatedengine and the override circuit component prevents the engine fromoperating by grounding the magneto.
 11. The control circuit of claim 1wherein the override circuit comprises first and second logic circuitsthat are coupled together and one of said logic circuits produces anoverride output and wherein one of the first and second overrideswitches changes a logic circuit input state and another of the firstand second override switches presents the change in logic state to theoverride output.
 12. A control circuit for a lawn tractor having anengine and a power take off driven implement comprising: a) an operatorpresence switch for detecting the presence of an operator on the lawnand garden tractor; b) a first override switch for allowing operation ofthe power take off driven implement when the lawn tractor is in reverse;and c) an override circuit component coupled to the operator presenceswitch and the override switch that allows operation of a power take offdriven implement while the lawn tractor is in reverse when the overridecircuit component is in a first state and inhibits operation of thepower take off driven implement while the lawn tractor is in reversewhen the override circuit component is in a second state; d) saidoverride circuit also preventing said power take off driven implementfrom operating when an operator is not sensed as indicated by theoperator presence switch.
 13. The control circuit of claim 12 whereinsaid operator presence switch and said override switch prevent saidpower take off driven implement from operating when an operator is notpresent and said override switch is in said first position by stoppingthe engine.
 14. The control circuit of claim 12 wherein said operatorpresence switch and said override switch prevent said power take offdriven implement from operating when an operator is not present and saidoverride switch is in said first position by disengaging an electricpowered clutch for activating the power take off driven implement. 15.The reverse operation control circuit of claim 12 wherein the engine isa magneto operated engine and the operator presence switch and theoverride switch prevent said engine from operating when an operator isnot present and the override circuit componenet is in a first state bygrounding a magneto.
 16. The control circuit of claim 12 wherein theoverride switch is formed by contacts of an ignition switch.
 17. Thecontrol circuit of claim 12 additionally comprising an additionaloverride switch and wherein both the first and the additional overrideswitches must be actuated to allow operation of the power take offdriven implement while the tractor is in reverse.
 18. The controlcircuit of claim 17 wherein one of said first and additional overrideswitches is a momentary switch that is temporarily actuated by a user toprovide said override state.
 19. A control circuit for a lawn tractorhaving an engine and a power take off driven implement comprising: a) abrake switch for detecting engagement of a lawn and garden tractorbrake; b) a first override switch for allowing operation of the powertake off driven implement when the lawn tractor is in reverse; and c) anoverride circuit component coupled to the brake switch and the overrideswitch that allows operation of a power take off driven implement whilethe lawn tractor is in reverse when the override circuit component is ina first state and inhibits operation of the power take off drivenimplement while the lawn tractor is in reverse when the overridecircuitcomponent is in a second state; d) said override circuit also preventingsaid power take off driven implement from operating when the gardentractor brake is engaged as indicated by the brake switch.
 20. Thecontrol circuit of claim 19 wherein the override has a bypass connectionfor allowing operation of the driven implement with the brake engaged.21. The control circuit of claim 19 wherein the engine is a magnetooperated engine and the brake switch and the override switch preventsaid engine from operating when the brake is engaged and the overrideswitch is in the first position by grounding a magneto to therebyprevent the PTO driven implement from operating.
 22. The control circuitof claim 19 comprising an additional override switch and wherein boththe first and the additional override switches must be closed to allowoperation of the power take off driven implement while the tractor is inreverse.
 23. Apparatus for use with a lawn tractor having an engine anda power take off driven implement; said apparatus comprising: an inhibitcircuit component for preventing operation of a power take off drivenimplement with the tractor in reverse; an override switch; an overridecircuit component that allows operation of a power take off drivenimplement while the lawn tractor is in reverse after the override switchis activated by a tractor operator; and a substrate for supporting saidinhibit circuit component, said override switch and the override circuitcomponent.
 24. The apparatus of claim 23 additionally comprising anindicator supported by said substrate to indicate a status of theoverride circuit component.
 25. The apparatus of claim 23 comprising asecond override switch electrically coupled to the override circuitcomponent and further comprising an ignition actuator that controls astate of the second override switch.
 26. The apparatus of claim 25wherein the ignition actuator is mounted to an ignition module thatdefines a housing that supports the substrate within a housing interiorand mounts to a tractor dashboard.
 27. A method for use in controllingoperation of a lawn tractor having an engine and a power take off drivenimplement; said method comprising: preventing operation of a power takeoff driven implement with the tractor in reverse absent an overridecondition determined by sensing a state of first and second overrideswitches actuatable by a tractor operator; allowing operation of a powertake off driven implement while the lawn tractor is in reverse in anoverride state after sensing actuation of the first and second overrideswitches by a tractor operator; and providing a visual indication on thelawn tractor to distinquish between an override and a non overridestate.
 28. The method of claim 27 wherein one of the override switchesis coupled to an ignition switch actuator and wherein actuation of saidone override switch must occur first before operation of the power takeoff driven implement is allowed with the tractor in reverse.
 29. Themethod of claim 27 wherein the visual indication of the override stateof the lawn tractor is provided by a light emitting device mounted to asubstrate which also supports one of said first and second overrideswitches.
 30. The method of claim 29 wherein the substrate is supportedby an ignition module that includes an ignition switch that definesanother of said first and second override switches.